WO2007/052994 describes a mobile telephone with a near field communication circuit (NFC-IC). Basic mobile telephone operation involves communication with base stations. An additional near field communication circuit in the mobile telephone enables the mobile telephone to interact locally with equipment like ticket selling machines or payment machines in the proximity of the mobile telephone. The mobile telephone may emulate a smart card for example, the near field communication circuit receiving power from the field of a card reader, to access a secure memory in the mobile telephone.
WO2007/052994 describes that the mobile telephone comprises a host processor coupled to the near field communication circuit using a standardized host communication interface (HCI). This interface enables the host processor to write commands to the near field communication circuit and to read data and configuration information from the near field communication circuit.
In mobile telephones the subscriber identification module (SIM card) may act as host for the near field communication circuit. In communication with the near field communication circuit, the SIM card sets up configuration data to define communication pipe states and handles. This type of configuration information is stored in a non-volatile memory in the near field communication circuit, to enable the near field communication circuit to operate independently under power from the field of a card reader. This introduces the risk of errors when the SIM card is exchanged. To prevent such errors, SIM cards and near field communication circuits operate on a session basis, with sessions defined by a “session id” number stored in the SIM card and near field communication circuit. The “session id” can be a randomly selected number. The SIM card tests whether the session id numbers match as a condition before starting cooperation with the near field communication circuit. Thus, it is prevented that replacement of the SIM card can lead to errors.
Increasingly, mobile communication equipment is equipment with a plurality of host processors. For example, in addition to a host in the exchangeable SIM card there may be a mobile host processor permanently installed in the mobile communication equipment (e.g. soldered to a substrate). Such a mobile host processor may be used to perform complicated control functions. Frequently, it is used as a supervisor that determines the extent to which other host processors are allowed to access the near field communication circuit or secure memories. Thus, it enables the user to control whether the mobile communication device can be used to make payments or not. Similarly, it may enable the user to control the ability to communicate directly with other mobile telephones.
Mobile host processors of portable communication devices suffer from frequent power down situations. Battery removal, user switch off and battery energy saving may all lead to frequent removal of power from the mobile host processor. Each time when power is switched on, communication with the near field communication circuit requires setting up a new configuration, which may introduce errors in the interaction between the near field communication circuit and other hosts or secure memory. Also, because the near field communication circuit stores configuration data in non-volatile memory, frequent mobile host power downs may reduce the useful lifetime of the near field communication circuit due to excessive wear of the non-volatile memory.